Self-contained water purifiers have been available for decades and principally are used in laboratory environments to provide highly purified, for example, ultra pure, reagent water. The highest quality reagent water conforms to or exceeds ASTM Type I standards which require water having a specific resistance of greater than 18.0 megohm-cm and a total organic carbon (TOC) content of no more than 100 parts per billion (ppb). Such water purifiers are normally connected to a water source which may, or may not, provide pretreatment. Further, the water purifiers have a manually operable dispensing valve fixed at a convenient location, for example, on a forward surface of the water purifier. When applications dictate the need for a capability of dispensing liquid remote from the purifier, in addition to a normal dispenser, a separate and independent dispenser is connected to the water purifier by means of flexible tubing. Therefore, to obtain the benefits of the capability of remote dispensing, a separate, redundant, manually operable dispenser is used. The additional dispenser not only substantially increases the cost of the system, but provides an additional potential source of water contamination from the surfaces required by the second dispensing valve. Therefore, such purifiers have the disadvantages of increased costs, as well as a reduced efficiency in removing contaminants to compensate for the additional impurities introduced by the remote dispenser.
Prior remote dispensers generally fall into one of two categories. A first category includes generally pistol-shaped dispensers in which the grip element is approximately perpendicular to the centerline of the dispensing outlet. Such dispensers are most conveniently used when fluid is to be dispensed in a stream or a spray at a relatively low elevation, for example, from hip level. However, in a laboratory, such pistol-shaped dispensers are more difficult to use when filling a container being held up at eye level in front of a user. For example, a flask having graduations on its side is most conveniently held approximately at head level so that the user may observe the flask graduations as fluid is being filled therein. Utilizing a pistol-shaped dispenser in such an application requires an awkward bending of the wrist, which makes precise operation of the trigger very difficult.
A second category of dispenser includes designs in which the grip is more in line with the dispenser outlet and forms an obtuse angle with the centerline of the dispenser outlet. Those dispensers also conveniently dispense fluid to be dispensed into a container at a lower elevation. In addition, the shape of those dispensers permits them to be grasped at a position forward of the dispensing control and held upside down for filling flasks that are of a higher elevation, generally at the eye level of the user. However, the dispensers are relatively large and bulky and not conveniently gripped by users having smaller hands. Therefore, it is possible to differently grip the second category of dispensers for different dispensing applications, their larger size makes such use awkward and hard to control.
Normally, remote dispensers have a recirculation capability, that is, when the dispensing outlet is closed, fluid continually recirculates through the dispenser so that any impurities leaching into the water are flushed away on a continuing basis. Consequently, the purifier remains in an "at ready" state to dispense reagent water. The designs of prior dispensers often permit a small quantity of water to reside between the dispensing valve and the point of use dispensing outlet, thereby avoiding the recirculation path. Consequently, over a period of time, for example, overnight, that non-recirculating, stationary water will often leach material from the dispenser components and, will further begin to stagnate and promote the growth of bacteria. In that situation, the fixed dispenser must be used until the remote dispenser can be cleaned, for example, by dousing in a bleach solution to rid it of the bacteria. Therefore, there is a need for an improved dispensing system to overcome the problems described above.